Slide rule



Nov. 9 1926. f 1,605,922

3. M. cooK SLIDE RULE original Filed'neo. 2s, 1922 6 5 @Jl l/ 9 9 /Z adjustment.

Patented .N ov. 9, A1926.

UNITED STATES itesm PATENT olf-FICE.

GEORGE 'M COOK,` OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-HALF TO THOMAS J'.

. MONAHAN, OF CHICAGO, ILLINOIS.

SLIDE RULE.

Application led December 28, 1922, Serial No. 609,534. Renewed April 3, 1926.

This invention relates to slide-rules and more especially to improved means for accurate setting and reading of such instruments. The ordinary rule of this sort has two'or more sets of. lineal graduations, some of which are on a sliding piece, so that some function of .a number on one ieee is formed opposite it on the other. generally both scales are graduated to the logarithms of the numbers on them, so that products may be read direct. ally supplied to facilitate setting and reading the device accurately. ,The successive .gage units are not uniform, but vary according to certain laws well known in the art. This characteristic augments the dificulty in obtaining accurate results. Heretofore, so far as I am aware, the runner settings have been obtained merely by direct manual operation, guided either by direct visual observation of the hairline and gage marks, or at most 'by the aid of a magnifying attachmentV limited to lengthwise enlargement of the scale.

The main objects of thisinvention are to provide for amplifying the practical utility range of slide-rules by rendering them more precise and convenient to operate; to provide positive mechanical means for setting of the runner according to fractions of a scale unit; to equi such a device with micrometric means a apted for securing great refinement and accuracy in this setting; to

provide readily adjustable means adapted to vary. the range of this supplementary apparatus so as to divide scale units of various lengths, whereby the application of the device may ybe extended to cover all ordinary uses of .the slide-rule; to provide an improved form of magnifying means; and to provide an improved and more convenient form of mounting or support for the magnifying lens, adapted for folding compactly and for readyI -manual shifting and An illustrative embodiment of this invention is shown by the accompanying in' which;

Figure 1 is a plan of the left end of an ordinary slide-rule'with the runner thereon. and showing the micrometric attachment on the right side of the runner. This elevation is'shown as looking through magnifydrawings,

ing lens, but to prevent misleading distor-` tion in drawing, no magnification is shown.

A hair-line runner is usu` Fig. 2 is mainly a longitudinal section substantially on the line 2-2 of Figure 1,.

Fig. 5 is an enlarged underside plan of the lever shoe for the hair-line link.

The construction of the iXed member and slide of the rule shown in the said drawings is the same as usually found in sliderules of this general character, the novelty of construction and operation being inthe runner and its attachments. The device as a whole, comprises a fixed member 1, a slide 2, and the runner 3. Said runner in turn comprises an oblongv frame 4 of special extended overhanging form, in combination with a hair-line plate 5 mounted slidably thereon, an adjustably mounted lens 6, and

a micrometer-like device 7 having adjustable connections extending to the plate 5 for setting the hair-line 8 von the rule gage to indicate precisely the fractional space desired. L

The runner frame 4 comprises a rear side bar 9, a front side bar 10, a left end cross bar 11, a right end cross bar 12, and a medial cross bar 18, said bars being fastened together rigidly by sc-rews 14, as shown in Figure 1. The left halves, more or less, of the two side bars are formed attheir lower edges with inwardly projecting anges 16,'

such as are usually provided on slide-rule runners to engage the corresponding grooves 17 formed in the edges of the fixed member 1. The right end halves approximately of said side bars are oiiset upwardly as at the 'medial points 18 suiiiciently to 'clear the member 1, and serve to support the micrometer attachment and its connections.

For the purpose of supporting the micrometer and certain associated parts, a plat-`V` form plate 19 is mounted with its upper face flush betweenthe cross bars12 and 18, and is manually slidable forwardly and backwardly thereon as will be more fully explained. On the left part of this plate is pivotally mounted the arcuately calibrated disk 20 which is carried pivotally by the screw 21. Said.` disk 20 is provided with a knurled head .22 adapted t facilitate turning by the thumb and finger, and is also provided with gage marks 23 which are variously spaced successively, as will be eX- plained. A co-relative stationary lmark or index pointer 23 is provided on plate 19.

0n the underside of said plate 19, and

secured to said disk coturnably, is a crank disk 24 which is provided with an arcuate notch 25 having anA effective angular range of (preferably one hundred and twenty degrees, the ends of which notch serve as shoulders 26 to engage a stop pin 27 set in the underside of said plate 19. Said crank disk 24 is also provided with a downwardly projecting crank pin inthe form of a'sc'rew 28 from which a link 29 extends toward the right. Said link 29 is secured by'a pivot screw 30 to'a longitudinally movable slide member 31 carried by platform 19, which member in turn is pivoted at its right end by means of screw 32 to a channel-like transversely disposed guide 33 for the horizon-v tally swinging transversely disposed lever'` 34. Said lever is also of channel shape and contains a longitudinally movable slide shoe 35 to which 1s pivotally connected, as by screw 36, a link 37 which leads to the left and is pivoted by screw 38 to the hair-line plate 5. Said shoe 35 vis yoke-shaped and its two arms 35 press outwardly by spring action against the side anges of lever 34. The screw 36 fits in the hole 35 of said shoe.

. The platform 19 is slidable manually by reasonV of the tongue'and groove construction shown at 39 on Figure 2. The movement of plate 19 is forwardly limited by the disk 24 contacting with bar 9, and rearwardly by shoe 33 contacting endwise against the stud-40 which carries the pivot screw 41 on which. lever 34 swings. The rearward swing of lever 37 is limited by the. shoe 35 contacting against the head of pivot screw 41, and its forward swing isarrested b the stop screw 42 on lever 34.

The sli e member 31 com rises a leftend body part having upwar y turned side' flanges 31 and a right end extension 31 4carrying the pivot 32,. Said flanges 31 embrace the longitudinally disposed guide block 43 fixed on the underside of .platform v19. Hence, the 1toand^fro movements of slide 31 and pivot 32 are rectilinear.

lhe lens 6 is-set in a frame 44 having a pair of foldably arranged sup orts 45 and 46 pivotally connected to the right and left edges, respectively.

The right support 45 is U-shaped with downwardlyl ro]ecting'sides,v havin outwardly turne ivots45 to enter horizontal holes inthe si e bars 9 and 10. The left sup ort 46 is free 4at its lower end and inclu es a crossw-ise part 46 which rests on therunner frame. The supports 45 and-46 are inclined somewhat convergently toward .the top. Hence the right side of the lens tilts downwardly slightly as it swings to the left and vice versa, though it stands horizontal in its normal position as shown by Figure 2.

Referring to Figure 1, it will be seen that turning the micrometer head 22- clockwise moves the hair-line plate 5 to the left, and vice versa, and the movement of plate 5 is nearly `proportional to the angular movement of dial plate 20. lnbrder to provide for this movement the crank pin 28 is positioned directlyin front of pivot 21 on disk 24 whenthe latter is midway between the limits of its movement as determined by the shoulders 26. That is to'say, the crank pin 28 swings-in -an arc so limited and disposed that its movement is not only nearly rectilinear but is substantially parallel with the direction of movement of the hair-line.

The oscillation range of plate 5 may be rincreased by pulling the free end of' link 37 forward and vice versa, for when pivot 36 is near the free end of lever 34 it swings farthest and when near pivot 41 it swings least, but its approachto pivot41 is limited as above explained. Said range may be further increased by pushing platform 5. back subject to the limitation above explained, and vice versa, for when the latform is ,pushed back the virtual actuating arm of said 'lever is shortened, and a given linear movement of pivot 30 augments the angular "throw ofsaid leverfthe efective-length of the arm which carries pivot 36 remaining unchanged. For practical purposes 4the units to be divided are relatively small;.

hence, the plate 19 is pulledv forward' and the lever 37 pushed back. For'larger units the lever 37l is pulled forward accordingly. The micrometer scale shown on disk 20 represents a harmonic division of the logarit mic scale.

'In use, if a fractional reading is to be taken' the lever 37 and plate 19 are set so that when diskI 20 is rotated through its range (120 degrees) the hair-line will traverse the unit distance concerned, the final .adjustment'being obtained by moving the late 19. This 1s accomplished by setting the' hairLline-at the left edge o'f the given unit with the disk 20J set at zero. Then the disk 20 is swung to its opposite position and the plate'19v is adjusted to bring th( hair-line exactly on the right edge of said unit. In doing this the hnk '37 may also vbe re-set-if necessary. Then with the hairline at the left edge of'the unit space and the disk 20 at zero said disk is turned counter-clockwise s'utliciently to -bring the hair-'line on the fractional setting in question. The desired fraction vin tenths Aof a unit may then be read on the disk 20. v

In a similar manneif, the hair-line may besetoh anydesiredhactionofaunitas lil ' follows z-First the plate 19 is adjusted to movement of the hair-line provide for unit of disk 20. Then when for a full swing the disk 20 is turned to the desired fraction,

the hair-line will be 'set accordinglyl on the fractional space. to be set ofi' on the rule scale.

` teenth Aof an inch. Hence,

of plate 5 and lever 3 4 is suflicient, and the The micrometer scale is calibrated sub stantially as follows .-The link 37 and plate 19 vare first adjusted relative to lever 34 ,so that a full swing of disk 20 will cause the hair-line to traverse some unit of the scale which is shown divided `into -ten parts (logarithmic). The disk 20 is then turned from -itsone extreme position to its other extreme position (120y degrees), and as the hair-line reaches successive division marks the'plate 20 is marked accordingly.

All of the scale units to be measured by this micrometer are smalL-not over. a sixa limited throw platform'19 is, therefore, pulled forward so as to limit the movement of said lever to a small arc. i

Although but one specific embodiment of this invention is herein shown and described, it is to be understood that numerousf details of the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following claim,

I claim: In a slide-rule runner, micrometric means and connections therefor, including a rotary index member, a lever pivoted to the runner frame, a member slidably connected to said lever in relatively turnable relation thereto, and a link connected at one end to an eccentric partof said index member and at its other end? to the slide member' whereby harmonic motion may be imparted-thereto by uniform turning of said index member.

Signed at Chicago this 26th day of December 1921. v.

- COOK. 

